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PCI/MSI: Prevent recursive locking in pci_msix_write_tph_tag()

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pci_msix_write_tph_tag() takes the per device MSI descriptor mutex and then
invokes msi_domain_get_virq(), which takes the same mutex again. That
obviously results in a system hang which is exposed by a softlockup or
lockdep warning.

Move the lock guard after the invocation of msi_domain_get_virq() to fix
this.

[ tglx: Massage changelog by adding a proper explanation and removing the
  	not really useful stacktrace ]

Fixes: d5124a9957 ("PCI/MSI: Provide a sane mechanism for TPH")
Reported-by: Jorge Lopez <jorge.jo.lopez@oracle.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jorge Lopez <jorge.jo.lopez@oracle.com>
Link: https://lore.kernel.org/all/20250708222530.1041477-1-himanshu.madhani@oracle.com
This commit is contained in:
Himanshu Madhani 2025-07-08 22:25:30 +00:00 committed by Thomas Gleixner
parent d7b8f8e208
commit 68ea85df15
1 changed files with 3 additions and 1 deletions
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4
drivers/pci/msi/msi.c
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@ -934,10 +934,12 @@ int pci_msix_write_tph_tag(struct pci_dev *pdev, unsigned int index, u16 tag)
if (!pdev->msix_enabled)
return -ENXIO;
guard(msi_descs_lock)(&pdev->dev);
virq = msi_get_virq(&pdev->dev, index);
if (!virq)
return -ENXIO;
guard(msi_descs_lock)(&pdev->dev);
/*
* This is a horrible hack, but short of implementing a PCI
* specific interrupt chip callback and a huge pile of